1. Field of the Invention
The present invention pertains to medication infusion systems, and more particularly to a fluid handling system for a medication infusion system.
2. Description of the Prior Art
The desirability of being able to infuse medication into a human or animal body has been recognized by prior and contemporary technology. Some such apparatuses are totally implantable while in others the pump and control apparatus is external to the living body and a catheter or the like is used to supply the medication to be infused into the living body. In either case delivering a medication flow which is controlled is imperative. Additionally, for infusion of medication such as insulin it is important that the infusion flow profile mimics that of insulin production in a normal person.
Another consideration, especially in implanted pumps, is that power consumption be kept to a minimum to insure adequate battery life.
To control the flow of medication from an infusion pump it has been suggested that a flow restrictor can be employed. Such flow restrictors are taught in U.S. Pat. Nos. 3,731,681, 3,894,538, 3,951,147 and 4,077,405. U.S. Pat. No. 4,299,220 teaches the use of a pressure regulation system in combination with a passive pump for infusing drugs.
The use of a fluid accumulator in combination with a fluid flow restrictor is taught in U.S. Pat. Nos. 4,192,397 and 4,221,219. Both of these patents employ a passive pump which operates under the principal of having pressure applied to a reservoir such that fluids stored within the reservoir is forced thereout. While such a pump configuration does not in and of itself require electrical consumption it basically is uncontrollable unless valves or the like are used to control flow from the pump.
The present invention solves the problems associated with the prior art by using a pulsatile pump in conjunction with an accumulator flow restrictor network to give the advantage of low power consumption since a pulsatile pump as taught herein is economical in electrical consumption by virtue of the use of spring force to pump and which also provides, in combination with the accumulator flow restrictor a delivery of medication which has a profile that is smoothed and therefore desirable for certain applications such as infusion of insulin.
A pulsatile pump is shown in the U.S. Pat. No. 4,152,098 but its use in combination with an accumulator flow restrictor is not shown or suggested.